Earth sciences

Dispersal mode as a selective force in shaping the chemical composition of seeds

Article Abstract:

Dispersal mode plays a role in modulating the chemical composition of seeds. Seeds usually dispersed by wind and animals possess greater amounts of fats than carbohydrates or proteins because fat reduces the size and weight of the seeds which increases the dispersal efficiency without changing the energy value of the seeds' resources. Therefore, more fats are stored by seeds of wind and animal-dispersed species inspite of the added energy cost in their synthesis as long as dispersal efficiency increases with reduction in sizes and weights of the seeds.

A model of caching depth: implications for scatter hoarders and plant dispersal

Article Abstract:

Foragers' ability to discover buried nuts and seeds depend on the depth of storage. Similarly, the depth of burial affect the survival of seedlings not found by foragers. The two patterns are considered in a caching depth model. Optimal burial depth for horders is the depth at which the difference between the energy stored in the cache and the energy required to produce and retrieve the cache is maximum. For seeds, optimal cache depth is the depth at which escape from forager is maximized without compromising survival.

Seeds of the wild parsnip, scientifically known as Pastinaca sativa, were collected to quantify the costs of furanocoumarins allocation in terms of total seed production. The role of furanocoumarins as a chemical defense against herbivorous insects was also analyzed. Results reveal that a high concentration of furanocoumarins is produced to effectively serve as a chemical defense against insects. However, results also show that this defense mechanism will be ineffective in the absence of the parsnip webworm.